1. Field of the Invention
This invention relates generally to wire knotters and, more particularly, to a method and apparatus for individually and selectively driving a plurality of wire knotters.
2. Related Art
Wire baling of bulk materials benefits from increased speed and reduced materials cost through automation. Bulk materials include fibrous bulk materials such as cotton and nylon. Fibrous materials are commonly formed into bales by simultaneous compression and binding. There is a continuing need in the automated baling art to improve the efficiency, reliability and accuracy of the bale binding process.
Baling wire performance requirements vary depending upon the bulk material being baled. Such requirements range from industry standard specifications to general operational parameters, such as minimum speeds required for profitability. The Cotton Council issues standard baling constraints specifying particular ranges for the length of wire around the bale and the tension that the wire must withstand.
Current automated baling machines use an articulated track to guide wire around bales of bulk material, while that bale is under compression. Part of the wire guide track in current automated balers must be removable to a second position after the ends of the baling wire have been tied together, in order to allow ejection of the bale and insertion into the baler of the next unit of material for baling. Material to be baled is typically introduced into the automatic baler under vertical compression. Typical pressures for an industry standard 500 pound, 20 by 54 inch bale are in excess of 300 tons. Horizontal plates called follower blocks apply compression through platens which contact the surface of the cotton or other material being compressed. The platens incorporate slots which run laterally to the longitudinal axis of the bale. The Industry Standard number of binding wires for cotton bales is six. Accordingly, there are six slots in the platens. These allow the baling wire to be wrapped around the bale while it is still under compression. The lateral slots have lateral channels behind them for insertion of wire guide tracks in both the upper and lower platens in automatic balers.
A knotter is connected to each track. Knotters operate internally by a receiving a leading end of a bale wire after it has been driven in a circle around the bale and overlapping that end with the trailing end of the wire that has been cut to the appropriate length. Each wire end is seated in a slot in a gear. The gears in the knotter are arranged to twist the ends in opposite directions, effectively twisting them together in a knot. These gears are driven by a shaft, which is in turn driven from outside.
Current machines, if they are to provide the desired feature of selectively engaging individual knotters, or disengaging other individual knotters, must individually drive each knotter. That is, a separate drive apparatus, typically a servo motor, must be engaged with the knotter drive shaft on each individual knotter. This solution to the problem of selectable individual engagement is obviously quite expensive. There is a need in the art for a more economical method and apparatus for achieving individual engagement selected.
It is not uncommon for a wire being looped around the bulk material to bind up in the track or otherwise misfeed. In this case, it is necessary to remove the bound up wire and retie the bale. Presently, there exists no easy or convenient method for retying the bale. Either the wire can be looped manually which presents some hazard to the operator, or alternatively the tied wires may be cut and the process begun again. There remains a need for an automatic baling apparatus that can correct mis-feeding errors.
U.S. Pat. No. 3,528,364 issued to Freund on Sep. 15, 1970 illustrates the problem in the existing art. The Freund patent discloses an apparatus for tying bales of material after it is compressed in a baling machine. In the Freund device, material is compressed into a bale, wire is looped around the bale, and both ends of the loop are placed in a twisting apparatus. The twisting apparatus consists of a several pinions and a vertical rack. Each pinion includes two diametrically opposed slots, and the loop ends are placed in these slots. When the vertical racks are displaced, the pinions rotate thereby twisting together the two ends of the loop. Because the pinions are in constant contact with the rack it is not possible to knot a single loop of wire.
There remains a need in the art for a more reliable and durable wire knotter drive that is capable of selective engagement of either a single knotter or a plurality of knotters.